<template>
  <div class="pagination" >
    <button :disabled="pageNo===1" @click="$emit('getPage',pageNo-1)">上一页</button>
    <button v-show="startEndPage.start >1" @click="$emit('getPage',1)">1</button>

    <button v-show="startEndPage.start>2">···</button>

    <button
        v-for="page in startEndArr"
        :class="{active:pageNo === page}"
        :key="page"
        @click="$emit('getPage',page) "
    >{{page}}</button>


    <button  v-show="startEndPage.end<totalPages-1">···</button>
    <button v-show="startEndPage.end<totalPages" @click="$emit('getPage',totalPages)">{{totalPages}}</button>
    <button :disabled='pageNo === totalPages' @click="$emit('getPage',pageNo+1)">下一页</button>

    <button style="margin-left: 30px">共 {{total}} 条</button>
  </div>
</template>

<script>
export default {
  name: "Pagination",
  props:['totalPages','pageNo','continuePage','total'],
  data(){
    return{
        isActive:0
    }
  },
  mounted(){
  //  setTimeout(()=>{
  //   //  console.log(this.startEndPage);
  //   //  console.log(this.totalPages,this.pageNo,this.continuePage)
  //  },2000)
  
  },
  computed:{
    startEndPage(){
        const {totalPages,pageNo,continuePage} = this;
      
      //连续页循环的开头和结束页码
        let start = 0 ,
        end = 0;
    
     // 先比较总页数和连续页的大小
    //  当总页数小于连续页的时候 开始页就为1 结束页就为总页数
     if(totalPages<continuePage){
        start = 1;
        end = totalPages;
     }else{
        start=pageNo-Math.floor(continuePage/2);
        end = pageNo+Math.floor(continuePage/2);
        if(start < 1){
            start = 1;
            // 当start<1的时候 end也小于continuePage 为了保证连续页为5 所以结束页等于连续页
            end = continuePage

        }
        if(end>totalPages){
            end = totalPages;
            start = totalPages - continuePage + 1
        }
     }
     return {start,end};

    },
    startEndArr(){
        const arr=[];
        for(var i = 1; i<=this.startEndPage.end;i++){
            if(i>=this.startEndPage.start){
            arr.push(i);
        }
    }
    return arr ;
  }
},
}
</script>

<style lang="less" scoped>
.pagination {
  button {
    margin: 0 5px;
    background-color: #f4f4f5;
    color: #606266;
    outline: none;
    border-radius: 2px;
    padding: 0 4px;
    vertical-align: top;
    display: inline-block;
    font-size: 13px;
    min-width: 35.5px;
    height: 28px;
    line-height: 28px;
    cursor: pointer;
    box-sizing: border-box;
    text-align: center;
    border: 0;

    &[disabled] {
      color: #c0c4cc;
      cursor: not-allowed;
    }

    &.active {
      cursor: not-allowed;
      background-color: #409eff;
      color: #fff;
    }
  }
}
</style>
